Is it permissible to urinate standing up?

It is makrūh (disliked) to urinate in a standing position without an excuse as it is against the Sunnah method (al-Baḥr al-Rāʾiq 1: 256; Marāqī al-Falāḥ, p. 27; Radd al-Muḥtār, 1: 344).

The mother of the believers, ʿĀʾishah (may Allah be pleased with her) is reported to have said: “Whosoever narrates to you that the Prophet ﷺ would urinate whilst standing, then do not believe him. He would not urinate except in a sitting position” (Sunan al-Tirmidhī, 12; Sunan al-Nasāʾī, 29).